Smoke rises from the area of a wildfire near Entiat, Wash., on, July 11, 2014. / Rachel La Corte, AP

by Gary Stoller, USA TODAY

by Gary Stoller, USA TODAY

Firefighters made progress Sunday battling a large wildfire that has burned thousands of acres of mountain wilderness in Washington state.

The wildfire - the largest of numerous ones burning in the West - started July 8 in Mills Canyon in Okanogan-Wenatchee National Forest, which encompasses more than 4 million acres along the eastern slopes of the Cascade Range.

The fire has burned 34 square miles and is 25% contained, said Daniel O'Connor, a U.S. Forest Service spokesman at the fire command center.

The fire did not grow in size before dark Sunday, but O'Connor said firefighters were concerned about forecasts of possible lightning storms without rain overnight that could ignite dry brush.

Residents of 37 homes were ordered to evacuate, and people in 48 others were told to be ready to leave, he said.

"It's been a real good day on the fire so far,'' O'Conor said. "Crews made a lot of progress.''

Dry lightning - cloud-to-ground lightning without accompanying rainfall - has a 90% chance of igniting sagebrush and grass in the national forest, O'Connor says.

The fire, which is southwest of the central Washington town of Entiat, is being battled by 781 firefighters, and its cause has not been determined, he says.

Wildfires have plagued the drought-stricken West for months.

President Obama last week asked the House to fund $615 million for "emergency wildfire suppression activities" for fiscal year 2014. The request was attached to a larger request for $3.7 billion for improved border security and other immigration concerns.

While dry, hot weather adds to firefighters' concerns in the Northwest, other regions of the country are facing severe weather conditions.

Thunderstorms are forecast for upstate New York, northern and western Pennsylvania and the lower Midwest states Sunday afternoon and evening, according to senior meteorologist Kristina Pydynowski at AccuWeather.com. The Northeast and Mid-Atlantic will face "severe thunderstorms and flooding downpours" through at least Tuesday, she says.

In the Midwest, the first part of this week "will feel more like September than the middle of July," Pydynowski says. Advancing cooler air will not only cause temperatures to drop but also bring rain and severe thunderstorms across the Ohio and Tennessee valleys, she says.

The high temperature in Chicago will be 77 degrees on Monday and 71 degrees on Tuesday - much lower than Seattle's highs of 89 degrees on Monday and 90 degrees on Tuesday, according to AccuWeather.com. Chicago's predicted low temperature on Monday - 55 degrees - will approach the city's record low for that date, 52 degrees in 1967.

Firefighters in the West probably wish they could have some of the rain predicted for the Midwest, but they have made strides on their own.

Another fire in Washington - east of Okanogan-Wenatchee National Forest - burned 400 acres in the Lake Chelan area and is 75% contained, O'Connor says. The fire, which began July 10, is expected to be fully contained Monday, he says.

Firefighters in Nevada were also successful in battling a wildfire that burned 15,246 acres in Washoe County, three miles south of the Oregon border.

The fire, which began July 1 "in a very remote area," is 98% contained and expected to be fully contained Monday, says Jeff Fontana, a Bureau of Land Management official.

In northern California, firefighters haven't made as much progress in a wildfire that has burned 3,700 acres in Shasta County. The fire is only 10% contained and is being fought by 1,056 firefighters, according to the California Department of Forestry and Fire Protection.

Freddie Alexander Smoke III, 37, was arrested Saturday and accused of causing the fire and illegal marijuana cultivation, the agency said. The exhaust from Smoke's truck allegedly ignited dry grass at an illegal marijuana plot, according to the agency.